def test_should_be_able_to_add_existing(self):
s = OrderedSet([1, 2, 3])
s.add(2)
assert list(s) == [1, 2, 3]
def test_should_be_able_to_add_new(self):
s = OrderedSet([1, 2, 3])
s.add(4)
assert list(s) == [1, 2, 3, 4]